Move PlatformScreen, PlatformScreenChromium, and Widget to Source/platform

BUG=297477

Review URL: https://codereview.chromium.org/27048004

git-svn-id: svn://svn.chromium.org/blink/trunk@159793 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Rebaseline css3/filters/effect-reference-hw.html due to http://src.chromium.org/viewvc/blink?revision=159692&view=revision

TBR=
BUG=

Review URL: https://codereview.chromium.org/27509003

git-svn-id: svn://svn.chromium.org/blink/trunk@159794 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Columns in 'window.onerror' handlers should be 1-based.

Columns in V8 stack traces are one-based[1], and IE10 matches that for
onerror handler arguments and the colno attribute of the error event. We
should match that as well for consistency.

[1]: https://code.google.com/p/chromium/codesearch#chromium/src/v8/src/messages.js&l=908

BUG=297845

Review URL: https://codereview.chromium.org/26851002

git-svn-id: svn://svn.chromium.org/blink/trunk@159795 bbb929c8-8fbe-4397-9dbb-9b2b20218538